Conventionally, in an image forming system for performing desired printing on a print sheet as a recording medium, when printing a large number of sheets (e.g., 500 to several thousand sheets) in consideration of productivity, an image forming apparatus capable of print processing at a high speed equal to or higher than 100 PPM (pages per minute) is known.
In high-speed and high-volume printing as above, as a post-processing device for the image forming apparatus, a paper discharge device capable of high-speed paper discharge in correspondence with the print speed is connected to the image forming apparatus.
In this type of paper discharge device, the print sheets subjected to the high-speed and high-volume printing are discharged in approximately horizontally toward a paper discharge table. The print sheets fall in a vertical direction, and the sheets are sequentially stacked on the paper discharge table. When the print sheets are simply discharged, the edges of the stacked paper sheets are not aligned. The print sheet pile easily collapses with an increase in the number of stacked sheets.
Further, the print sheet pile may be subjected to aligning operation with a regulating member (fence) in accordance with paper discharge speed. However, to conduct the aligning operation in accordance with high-speed paper discharge, it is necessary to enlarge a fence driving motor, which enlarges the entire device.
A paper discharge device disclosed in Patent Literature 1 has a configuration to suppress shifts of stacked print sheets. The device has fences for alignment fixedly provided in positions, slightly away from the positions of the respective ends of a print sheet placed on the table (the front side end in a paper discharge direction, the rear side end in the paper discharge direction, and ends in a print sheet width direction orthogonal to the paper discharge direction), in consideration of movement of print sheets upon paper discharge.
Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2014-61978